Vital sign monitoring apparatuses and methods of using same

ABSTRACT

A system for vital sign measuring of a patient, comprising: a first sensor removably attachable with a first body portion of the patient and configured to measure, when in operable position, a vital sign of the patient; at least one additional sensor removably attachable with a second body portion of the patient and configured to measure, when in operable position, a vital sign of the patient; and a processor configured to provide data descriptive of a level of correspondence between measurements of the vital signs provided by the first sensor and the at least one additional sensor.

RELATED APPLICATIONS AND PRIORITY

This application is a continuation of U.S. patent application Ser. No.15/552,469 filed on Aug. 21, 2017, which is a National Phase of PCTPatent Application No. PCT/IL2016/050218 having International filingdate of Feb. 25, 2016, which claims the benefit of priority of U.S.Provisional Patent Application Nos. 62/120,545 filed on Feb. 25, 2015and 62/136,741 filed on Mar. 23, 2015, entitled VITAL SIGN MONITORINGAPPARATUSES AND METHODS OF USING SAME. The contents of the aboveapplications are all incorporated by reference as if fully set forthherein in their entirety.

TECHNICAL FIELD AND BACKGROUND

Disclosed embodiments relate to the health care industry and, moreparticularly, but not exclusively, to a system and apparatus formonitoring and/or measuring vital signs.

In general, known devices may be unsuitable to provide sufficientaccurate and robust indication as to whether and when a patient's healthcondition is expected to deteriorate. This is true not only for patientswhose vital signs parameters are collected only periodically, forexample, every few hours in the hospital or through home-care, but mayalso hold for patients hospitalized in Intensive Care Units (ICUs) wheretheir vital signs may be constantly monitored.

SUMMARY

Aspects of disclosed embodiments relate to a system for vital signmeasuring of a patient.

According to example 1, the system comprises a first sensor removablyattachable with a first body portion of the patient and configured tomeasure, when in operable position, a vital sign of the patient; atleast one additional sensor removably attachable with a second bodyportion of the patient and configured to measure, when in operableposition, a vital sign of the patient; and a processor configured toprovide data descriptive of a level of correspondence betweenmeasurements of the vital signs provided by the first sensor and the atleast one additional sensor.

Example 2 includes the subject matter of example 1 and, optionally,wherein the first sensor comprises a first plethysmograph removablyattached to a first finger of a patient; wherein the at least oneadditional sensor comprises a second plethysmograph removably attachedto a second finger of the patient; the system further comprising apressure cuff removably between the first plethysmograph and theipsilateral palm of the patient; and an inflation device configured toinflate the pressure cuff; wherein the processor is configured toprovide data descriptive of a level of correspondence between signalsreceived from the first and second plethysmographs.

Example 3 includes the subject matter of any of examples 1 to 3 and,optionally, wherein the at least one additional sensor is at least oneof an accelerometer, a thermometer, a sound meter or a digital pressuresensor or a combination thereof.

Example 4 includes the subject matter of any of the preceding examplesand, optionally, wherein the processor is further configured to performat least one of commanding the inflation device, sending to andreceiving signals from the sensor and the at least one additionalsensor, sending to and receiving signals from the pressure cuff, andcorrecting or weighting received signals from the first sensor and theat least one additional sensor.

Example 5 includes the subject matter of any of the preceding examplesand, optionally, wherein the processor is located remotely from thepatient.

Example 6 includes the subject matter of any of the preceding examplesand, optionally, wherein the signals in the system are communicatedwirelessly.

Example 7 includes the subject matter of any of the preceding examplesand, optionally, wherein the system is configured to be wearable by thepatient.

Example 8 includes the subject matter of any of the preceding examplesand, optionally, wherein at least a portion of the system is configuredto be wearable by an attending medical professional.

Example 9 includes the subject matter of any of the preceding examplesand, optionally, further comprising a deflation device for deflating thepressure cuff in a controllable manner.

Example 10 includes the subject matter of any of the preceding examplesand, optionally, wherein the processor determines from received signalsat least one of systolic blood pressure, diastolic blood pressure, meanarterial pressure, pulse rate, breathing rate, breathing pattern,saturation level, motor function, temperature and, cognitive ability ofthe patient.

Example 11 includes the subject matter of any of the preceding examplesand, optionally, wherein the level of correspondence is expressed ascorrelation.

Example 12 includes the subject matter of example 1, where the processorcomprises at least one of a motor controller, a micro controller and ananalog front-end.

Example 13 includes the subject matter of example 2, where the inflationdevice comprises at least one of a pump and a valve.

Example 14 includes a method for vital sign measuring, comprising:removably attaching a first sensor to be in an operable position to afirst body portion of the patient for measuring a vital sign of thepatient; removably attaching at least one additional sensor to be in anoperable position to a second body portion of the patient for measuringa vital sign of the patient; and determining a level of correspondencebetween a first signal from the first sensor and at least one additionalsignal received respective of the at least one additional sensor.

Example 15 includes the subject matter of example 14 and, optionally,wherein the first sensor comprises a first plethysmograph removablyattachable to a first finger of a patient; wherein the at least oneadditional sensor comprises a second plethysmograph removably attachableto a second finger of the patient; wherein the method further comprises:inflating a pressure cuff attached to the first finger between the firstplethysmograph and a respective ipsilateral palm of the patient;determining a level of correspondence between a first signal from thefirst plethysmograph and a second signal from the second plethysmograph;and determining the systolic blood pressure of the patient based on achange in the level of correspondence.

Example 16 includes the subject matter of example 14 and, optionally,wherein the at least one additional sensor comprises an accelerometerfor detecting motion of the at least a portion of the patient.

Example 17 includes the subject matter of example 14 and, optionally,wherein the at least one additional sensor comprises a thermometer forassessing vasodilation in response to warming of the at least a portionof the patient.

Example 18 includes the subject matter of example 14 and, optionally,wherein the at least additional sensor comprises a sound meter formeasuring sound level of the patient.

Example 19 includes the subject matter of example 14 and, optionally,wherein the at least one additional sensor is removably attached to asecond body portion to detect additional information relating to vitalsigns of the patient to correct data descriptive of signals receivedfrom the first sensor.

Example 20 includes the subject matter of any of the examples 14 to 19and, optionally, further comprises determining the diastolic bloodpressure.

Example 21 includes the subject matter of example 19 and, optionally,wherein the at least one additional sensor is an accelerometer.

Example 22 includes the subject matter of any of the examples 14 to 21and, optionally, further comprising using an oscillometric method fordetermining systolic blood pressure, diastolic blood pressure or both.

Example 23 includes the subject matter of example 15, further comprisingrepeating inflating and deflating the pressure cuff a plurality of timesto determine diastolic blood pressure.

Example 24 includes the subject matter of example 23, where diastolicblood pressure is determined to be where a jump in the first signaloccurs.

Example 25 comprises a method for vital sign measuring, includingremovably attaching at least one accelerometer to a first hand of apatient; placing the first hand of the patient on the patient's abdomenor chest; and measuring motion detected by the at least oneaccelerometer to determine at least one of a breathing pattern andbreathing rate of the patient.

Example 26 includes the subject matter of example 25 and, optionally,further comprising removably attaching at least a second accelerometerto a second hand of the patient and having the patient place the secondhand in a different location on the patient's body than the first handto determine a breathing pattern of the patient.

Example 27 includes the subject matter of example 25 and, optionally,wherein the breathing pattern comprises a breathing rate.

Example 28 comprises a wearable system for vital sign measuringincluding an at least partial glove garment, comprising a first fingersleeve and a second finger sleeve and a palm portion; a firstplethysmograph coupled with the first finger sleeve; a secondplethysmograph coupled with the second finger sleeve; a pressure cuffcoupled with the first finger sleeve between the first plethysmographand the glove's palm portion; and an inflation device coupled with thegarment and configured to inflate the pressure cuff

Example 29 includes the subject matter of example 27 and, optionally,further comprising a processor configured to determine a level ofcorrespondence of signals received from the first and secondplethysmographs coupled with the first and second finger sleeves,respectively, or the harness.

Example 30 includes a system for determining a mental state of a person,the system comprising at least one accelerometer; and a processorcoupled with the at least one accelerometer, wherein the processor isoperative to determine a mental state of the patient based on datadescriptive of signals received from the accelerometer.

Example 31 includes a method of gauging vital sign parameters,comprising monitoring one or more vital signs of a patient using awearable vital sign measuring system during an activity.

Example 32 includes the subject matter of example 31, where a vital signis at least one of systolic blood pressure, diastolic blood pressure,mean arterial pressure, pulse rate, breathing rate, breathing pattern,hemoglobin oxygen saturation level, motor function, temperature orcognitive ability of the patient.

Example 33 includes the subject matter of example 31 or example 32,where an activity is at least one of working, performing physicalexercise, resting or sleeping.

Example 34 includes the subject matter of any of the examples 31 to 33,and further includes storing monitored vital signs of the patient duringthe activity.

Example 35 includes the subject matter of any of the examples 31 to 34,and further includes establishing whether a value of a vital signparameter corresponds to an expected value, taking into account thecurrent activity of the patient monitored.

Example 36 includes the subject matter of example 34, and furtherincludes providing an output indicative of at least one of a forecast orsuggestion of one or more treatment options based on data descriptive ofstored vital sign values.

Example 37 includes a method of assessing patient ability, comprising:instructing the patient to perform a reference movement; and, recording,using a wearable vital sign measuring system, a first patient movementdata set descriptive of the movement performed by the patient whenattempting to copy the reference movement.

Example 38 includes the subject matter of example 37, and furtherincludes comprising recording a second patient movement data setdescriptive of the movement performed by the patient when attempting tocopy the reference movement, and comparing the second patient movementdata set to the first patient movement data set.

Unless otherwise defined, all technical and/or scientific terms usedherein have the same meaning as commonly understood by one of ordinaryskill in the art to which the disclosed embodiments pertain. Althoughmethods and materials similar or equivalent to those described hereincan be used in the practice or testing of embodiments of the invention,exemplary methods and/or materials are described below. In case ofconflict, the patent specification, including definitions, will control.

In addition, the materials, methods, and examples are illustrative onlyand are not intended to be necessarily limiting.

Implementation of the method and/or system of embodiments of thedisclosed embodiments can involve performing or completing selectedtasks manually, automatically, or a combination thereof. Moreover,according to actual instrumentation and equipment of embodiments of themethod and/or system of the invention, several selected tasks could beimplemented by hardware, by software or by firmware or by anycombination thereof, using for instance an operating system.

For example, hardware for performing selected tasks according todisclosed embodiments may include a chip and/or a circuit. As software,selected tasks according to disclosed embodiments could be implementedas a plurality of software instructions being executed by a computerusing any suitable operating system. In an embodiment, one or more tasksthat may be associated with embodiments of the method and/or system asdescribed herein may be performed by a processor, such as a computingplatform for executing the plurality of instructions. Optionally, theprocessor includes and/or is operatively coupled with a volatile memoryfor storing instructions and/or data, and/or a non-volatile storage, forexample, a magnetic hard-disk and/or removable media, for storinginstructions and/or data. Optionally, a network connection is providedas well. An output device, for example, a display, and/or a user inputdevice, for example, a keyboard and/or mouse are optionally provided aswell.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Some embodiments are herein described, by way of example only, withreference to the accompanying drawings. With specific reference now tothe drawings in detail, it is stressed that the particulars shown are byway of example, and not necessarily to scale, and are for purposes ofillustrative discussion of the embodiments. In this regard, thedescription taken with the drawings makes apparent to those skilled inthe art how embodiments may be practiced.

In the drawings:

FIG. 1 is a schematic block diagram of a vital sign measuring system, inaccordance with an embodiment;

FIG. 2 is a flowchart of a method of using a vital sign measuringsystem, in accordance with an embodiment;

FIG. 3A is a graph of detected plethysmograph readings from a firstfinger (with a pressure cuff) and a second finger over time using afirst protocol, in accordance with an embodiment;

FIG. 3B is a graph showing the pressure within the pressure cuff overtime, where the time axis corresponds to the time axis of FIG. 3A, inaccordance with an embodiment;

FIG. 3C is a graph showing a correlation between plethysmograph readingsfrom the first finger and the second finger where the time axiscorresponds to the time axis of FIG. 3A, in accordance with anembodiment;

FIG. 3D is a graph of a triaxial accelerometer reading, theaccelerometer applied on one of the patient's hand which is placed onhis/her chest, where the time corresponds to the time of FIG. 3A, inaccordance with an embodiment;

FIG. 3E is a graph of the alternating component of the plethysmographsignal for each of the fingers, in accordance with an embodiment;

FIG. 3F is a bar showing the pressure buildup in the pressure cuff, inaccordance with an embodiment;

FIG. 3G is a histogram showing the correlation between theplethysmograph correlation (Y axis) and pressure level of the pressurecuff (X axis), in accordance with an embodiment;

FIG. 4 is a schematic block diagram of an alternative vital signmeasuring system, in accordance with an embodiment; and,

FIGS. 5A-5C are signal outputs of detected plethysmograph readings froma first finger (with a pressure cuff) and a second finger over timeusing the second protocol, where each of FIG. 5A-5C represents adiscrete progression through the second protocol, in accordance with anembodiment of the invention.

DETAILED DESCRIPTION

Disclosed embodiments relate to the health care industry and, moreparticularly, but not exclusively, to a system and apparatus formonitoring and/or measuring vital signs.

The disclosed embodiments are not necessarily limited in its applicationto the details of construction and the arrangement of the componentsand/or methods set forth in the following description and/or illustratedin the drawings and/or the Examples. The embodiments are capable ofbeing practiced and/or carried out in various ways.

In the health care industry, current oscillometric methods arerelatively accurate in measuring Mean Arterial Pressure (MAP) but muchless accurate in determining systolic/diastolic pressure. In practice,when deflating a blood pressure measurement cuff, one first “passes” thesystolic pressure. However, the signal indicative of the systolicpressure is spread out over a relatively large pressure range and istherefore inaccurate.

Further deflation of the cuff results in a pressure level where the cuffresonates, which is conventionally interpreted to be at the MAP.

Additionally, because the diastolic pressure is calculated based on aformula from the determined systolic blood pressure and/or mean arterialpressure, it is also subject to inaccuracy as a result of shortcomingsthat are associated with the determination of the systolic bloodpressure and employment of a mathematical formula rather than directmeasurement. In addition, the algorithms that are employed toextract/derive the systolic and/or diastolic blood pressure vary fromcompany to company and not standardized.

Generally, a system is provided which is configured to accurately,quickly and/or non-invasively measure and/or monitor at least onepatient vital sign, for example, systolic blood pressure, diastolicblood pressure, mean arterial pressure, pulse rate, breathing rate,breathing pattern, hemoglobin oxygen saturation level, motor function,temperature and/or, cognitive ability, in various clinical scenarios,including for emergency medicine and/or acute care scenarios. In someembodiments, multiple vital signs are measured using the same systemusing different types of sensors and/or modalities, enabling betteraccuracy and/or inter-parameter physiologic “reality checks” and/orredundancy and/or synergistic noise reduction. In some embodiments, thesystem is configured with a modular design, described in more detailbelow.

In some embodiments, by employing wearable device, the system isoperative to monitor one or more vital signs of the patient who may, atthe same time, engage in everyday activities including, for instance,working, performing physical exercise, resting or sleeping. It is notedthat the values of vital sign parameters may be affected by thepatient's activity. For example, when exercising, the patient's heartrate may increase compared to the heart rate when in a resting state. Asan additional example, the patient's blood pressure during sleep may bereduced compared to waking blood pressure. In some embodiments, thesystem may be configured to establish whether a value of a vital signparameter corresponds to an expected value, taking into account thecurrent activity of the patient monitored.

The system is further operative to provide long-term storage of datadescriptive of values of measured vital sign parameters. The system mayfor example be operative to store such data descriptive of vital signsand display the history of the values of vital signs monitored (e.g., ahistorical trend) for hours (e.g., 24 hours at least); days (e.g., 7days at least), weeks (e.g., 4 weeks at least), months (e.g., 6 monthsat least) or years (e.g., 2 years at least) and, optionally, provide anoutput indicative of a forecast and/or suggestion one or more treatmentoptions based on the data descriptive of past values. Such output mayadditionally or alternatively comprise raising an alarm, initiating acall to a caregiver, cause more frequent measurements, and the like.

The system may be operative to provide outputs of values of monitoredvital signs parameters meeting medical grade. The system's outputs maythus meet the requirements set by a “Gold Standard”, which may refer toany standard that may meet regulatory requirements and/or that is widelyor internationally accepted by the medical and/or scientific communityas a benchmark.

The assessment of measurement accuracy of blood pressure for a given BPdevice for example can be determined according to the standard proposedby the British Hypertension Society (BHS) and the US Association for theAdvancement of Medical Instrumentation (AAMI). For the standard proposedby the BHS, grading criteria are defined as cumulative percentage ofreadings falling within a certain BP range.

According to some embodiments of the devices, systems and methodsdisclosed herein achieve Grade A of available Grades A to Grade Daccording to the BHS-defined standard, i.e., at least 60% of thesystolic and diastolic measurements performed fall within the goldstandard measurement, +/−5 mmHg.

Referring now to the drawings, FIG. 1 is a schematic block diagram of avital sign measuring system 100, in accordance with an embodiment. Thesystem 100 comprises in an embodiment a first sensor 102 a and at leastone additional sensor 102 b. The first sensor 102 a may be embodied by afirst plethysmograph and the at least one additional sensor 102 b may beembodied by a second plethysmograph. The first and secondplethysmographs may be implemented as dual wavelengthphotoplethysmographs. Optionally, each of the plethysmographs 102 a/102b is removably and operably attachable (e.g. to the patient's fingers).For example first plethysmograph 102 a may be engaged with the indexfinger and the second plethysmograph 102 b with the middle finger of thesame (ipsilateral) hand. Alternative configurations may be conceived.For instance, first plethysmograph 102 a may be engaged with a finger ofa first hand and second plethysmograph 102 b may be engaged with afinger of the patient's other hand. The fingers may be in someembodiments contralateral.

In an embodiment, a pressure cuff 104 for applying an occluding pressureon the finger is applied on one of the fingers between the palm and theplethysmographs on that finger. In an embodiment, an inflating/deflatingdevice 106 for inflation/deflation of the pressure cuff 104 as well as amemory 109 and a power module 110 for enabling the powering of thevarious components of system 100 may also be provided. Theinflating/deflating device 106 may for example be embodied by a portable(e.g., wearable) electronically and/or mechanically operable device,which may be lightweight. The inflating/deflating device may for exampleinclude a controllable pump or a syringe that operably coupled with avalve for enabling control of flow rate during deflation for example ofthe pressure cuff 104.

In an embodiment, the at least one additional sensor 102 b may furthercomprise a digital pressure sensor and/or at least one accelerometerand/or a sound meter and/or a temperature sensor, and/or a sensoroperative to provide an indication about arterial (e.g., peripheral)tone and, based on the indication, provide an output indicative of achange of a physical condition of the patient such, for example, a sleepstate and/or condition (e.g. sleep apnea, onset of REM sleep state)and/or of heart function or condition (e.g., myocardial ischemia) forexample.

In some embodiments, a wearable pressure sensor may be operativelycoupled with the cuff 104 for measuring the pressure in the cuff and forproviding the processor with data descriptive of the measured pressure.

In an embodiment, at least one additional sensor 102 b (in addition tothe second plethysmograph) is wearable and/or is positioned on thepatient to function synergistically with the first and secondplethysmographs, for example at least one accelerometer is located inthe vicinity of the first and/or second plethysmograph to assist withcorrection of the readings from the nearby plethysmograph based onsensed motion of the patient from the accelerometer. In an embodiment, asound meter may engage a body part of the patient in an operableposition for measuring sound level in a sleep study. In an embodiment, atemperature sensor, in operable position, may be used for assessingvasodilation in response to warming.

In some embodiments, additional sensor(s) 102 b may also include atleast one accelerometer that can be operatively coupled with a part(e.g., finger) of one of the patient hands. The patient may place thehand with the accelerometer coupled thereto onto his/her chest orabdomen so that the accelerometer can sense changes in movements of thechest or the abdomen. These sensed changes can then be used by system100 for determining the patient's breathing pattern, which may forinstance include a breathing rate. In some embodiments, the at least oneadditional sensor 102 b may include a second accelerometer that can beoperatively coupled with a part of the patient's other hand. The twoaccelerometers may for example be used for substantially simultaneoussensing of movements of the chest and the abdomen for example by placingone of the patient's hands on his/her chest and the other hand onhis/her abdomen.

In an embodiment, at least one accelerometer is used to assess patientcapability, mental or physical or both. For example, while removablyattached to at least one accelerometer of the system the patient isrequested to perform a certain motion or series of motions which theaccelerometer measures. The measured motion is compared to an expectedperformance value in order to gauge the condition of the patient.

In some embodiments, a patient may be asked or trained to perform (e.g.,mimic) a given reference movement, which may herein also include asequence of movements. The system may record first data (“first patientmovement-data”) descriptive of the movement performed by the patientwhen attempting to copy the given reference movement, using one or moresensors (e.g., accelerometers). A patient's later performed movement maybe identified by the system as corresponding to the given referencemovement. Second patient-movement-data descriptive of such latermovement performed by the patient may be compared with the firstpatient-movement-data and analyzed. In some embodiments, the patient mayattempt to perform the given reference movement responsive to being cuedto do so, e.g., automatically by the system or by a medical professional(e.g., a care giver). The medical professional may communicate with thepatient over a communication network (not shown).

The system 100 may comprise a processor/controller 108. In someembodiments, the processor 108 may execute instructions stored in memory109 resulting in performing at least one of the following operations:receiving data from the at least one additional sensor 102 b;controlling the inflating/deflating device 106; handlingcommunication/alerts between system 100 components, the user and/or thepatient; schedules “data collection” depending on the care scenario, forexample different patients in different scenarios may need frequency ofmeasurements and/or different alarm limits (e.g. for a criticallyinjured soldier in the field or for a patient in an evacuationhelicopter, a continuous or almost continuous measurement of at leastsome of the vital signs is warranted, whereas for a stable, ambulating,and/or low risk patient in a ward in the hospital perhaps only onceevery 6 hours); and/or handles signal processing. In an embodiment,communication within the system 100 and/or to and/or from the system(e.g. to the patient, attending medical professional, user of thesystem, etc.) can be wired and/or wireless. In some embodiments,processor 108 may be embodied by an on-board processor 108. The system100 may be configured to be in operative communication with acommunications network, for example the Internet, local hospital serversor remotely located servers, the “cloud”, and the like. Some processingand/or data storage tasks are performed remotely on remote processorsand/or databases. In some embodiments, the system 100 is configured forcommunications based on the anticipated use of the system 100. Forexample, a system 100 configured for battlefield and/or ambulatory usemay have a more robust wireless communications capability (e.g. morebandwidth) than a system 100 in a hospital use scenario.

In an embodiment, at least one component of the system 100, for examplethe processor 108, executes a computer software program. In anembodiment, a user interface is provided for controlling and/or settingbehavior or performance of the system 100. The system may thus comprisea computer-program product. For example, varying sensitivity of thesystem, setting alarm thresholds for vital signs, and/or enablingwarnings for poor signal quality as determined for example by asignal-to-noise ratio and/or any other quality-related threshold (e.g.to and/or from sensors in the system 100, to and/or from remotecomponents of the system 100, to and/or from a communications network)can be controlled through the user interface.

In some embodiments, the processor 108 handles plethysmograph relatedtasks including processing heart rate, determining a level ofcorrespondence (e.g., correlation) between plethysmograph readings,oxygen saturation, pulsatile (“AC”)/constant (“DC”) component,determination of breath rate, heart rate and/or volume changes, depth ofanesthesia, and/or vasodilatation/constriction (temperature, medication,assessment of shock).

While embodiments exemplify the use of correlation for determining alevel of correspondence, this should by no means to be construed aslimiting.

In some embodiments, the processor 108 handles pressure sensor relatedtasks including determining systolic blood pressure (by return of aplethysmograph signal) and/or systolic and diastolic blood pressure(using an oscillometric method).

In some embodiments, as already indicated herein above, the processor108 handles accelerometer related tasks including ascertainingrespiratory rate (breaths per minute) when hand placed onthorax/abdomen, and/or motion detection for noise-reduction from atleast one sensor.

In some embodiments, the processor 108 handles integration of thereceived sensor data including noise reduction, including dynamic bandpass filters based on motion detection, reduction of “noise” caused byother physiologic processes (e.g. breath rate on heart rate),determination of value of a vital sign after analyzing modalities (e.g.which systolic, diastolic and/or mean arterial blood pressure todisplay: whether from an oscillometric calculation or from a return of aplethysmograph signal pressure or a synthesis of both; and/or arespiratory rate from a plethysmography waveform and/or from at leastone accelerometer).

In an embodiment, all components of the system 100 described herein arewearable and/or are human transportable. For example, in an embodimentvarious components of the system 100, the various sensors such as theplethysmographs, the pressure cuff, the inflation/deflation device, thememory, power module and/or the processor and/or, are provided togetherin a hand-wearable glove or partial glove whereby all of the componentscan be removably attached or placed onto the patient, in the correctlocations on the patient and/or relative to each other, relativelyquickly and conveniently. Optionally, at least a portion of the glove isflexible, for example because the pressure cuff is integral to the gloveand the cuff portion of the glove reversibly stretches in response toinflation of the cuff. In some embodiments, at least a portion of thesystem, for example the processor, is located in a bag or pack or on aharness or belt to be worn by the patient or the attending medicalprofessional or both.

In some embodiments, the system 100 is modular. For example, all of thecomponents are integrated into a single unit. In an embodiment, thesystem 100 is divided between the patient and an attending medicalprofessional, for example at least one of the plethysmographs, thepressure cuff and the additional sensors are positioned on the patient,while the processor is located on the attending medical professional. Inanother embodiment, at least one of the plethysmographs, the pressurecuff and the additional sensors are positioned on the patient and theprocessor is located remotely from the patient (i.e. via acommunications network such as the Internet).

FIG. 4 is a schematic block diagram of an alternative vital signmeasuring system 400, in accordance with an embodiment of the invention.Some of the system 400 components are the same as, or similar to,equivalent components in system 100. Reference numbers for system 400follow the reference numbers for system 100 (e.g. pressure cuff 104 issimilar to or is actually the same as pressure cuff 404, first sensor102 a is similar to or is actually the same as first plethysmograph 402a), although some components are not present and/or specifically shownin each diagram. Optionally, some of the components of system 400 aresubsumed by more general components described in system 100. Optionally,some of the components of system 400 are in addition to componentsdescribed in system 400. Optionally, system 100 has components notdescribed with respect to system 400. For the sake of brevity, exemplarydistinctions between system 100 and system 400 are described.

In an embodiment of the invention, system 400 inflating/deflating devicemay for example include a controllable pump 406 a or a syringe that isoperably coupled with a valve 406 b for enabling control of flow rateduring deflation for example of the pressure cuff 404.

In an embodiment, the at least one additional sensor 402 b may furthercomprise a digital pressure sensor 402 biii and/or at least oneaccelerometer 402 bii and/or any of the other sensor types referencedherein, for example.

In an embodiment of the invention, processor 108 of system 100 has afunctional equivalent in system 400 which includes at least one of amotor controller 408 a, a micro controller 408 b, and an analogfront-end 408 c. In an embodiment of the invention, motor controller 408a optionally controls the pump 406 a. In an embodiment of the invention,the analog front-end 408 c is used to provide a configurable and/orflexible electronics functional block, to interface the sensors 402 a,402 b with the motor controller 408 a and/or the micro controller 408 b.

In an embodiment of the invention, a user interface 412 is provided tofacilitate user interaction with system 400. Optionally, a radiotransmitter 414 and/or other communications equipment is provided tosystem to enhance connectivity.

It should be understood that either system 100, 400 is useable with thefirst protocol described herein with respect to FIGS. 2 and 3A-3G andthe second protocol described herein with respect to FIGS. 2 and 5.

FIG. 2 is a flowchart 200 of a method of using a vital sign measuringsystem 100, 400, in accordance with an exemplary embodiment, the methodis a plethysmograph correlation-based method that provides a more“direct” or straightforward approach of determining, at the very least,systolic blood pressure compared to prior, conventional methods ofdetermining systolic blood pressure. The methods described herein morequickly determine the systolic blood pressure, requiring less timeand/or caution when deflating the pressure cuff than is currentlypracticed in order to avoid missing the threshold of conventionalmethods indicative of the systolic blood pressure.

In an embodiment, a patient is removably connected to the system 100,400 by placing (202) a first plethysmograph 102 a on a patient's firstfinger and a second plethysmograph 102 b on a patient's second finger.In an embodiment of the invention, at least another sensor 102 b, suchas those described herein are positioned (204) on the patient, forexample at least one accelerometer. In an embodiment, a pressure cuff104 is removably attached (206) to the first or second finger, betweenthe patient's palm and the plethysmograph.

Systolic blood pressure is determined (208), in an embodiment, bydetermining correlation between data descriptive of signals receivedfrom the first and second plethysmographs 102 a/102 b. Variousoperational parameters and/or patient driven measurements are displayedby the system 100 to at least a user of the system 100, 400, for exampleas are shown in FIGS. 3A-3G. In an embodiment, a correlation isdetermined over a window of time during which signals from theplethysmographs 102 a/102 b are received by the system 100, 400.Optionally, the window is about 1 second.

Optionally, the window is shorter or longer in time. In an at restcondition of the patient, the correlation between the signal from thefirst plethysmograph 102 a and the second plethysmograph 102 b should beclose to 1, that is they should be very close to the same. In anembodiment, when the pressure cuff 104 is activated (210) to inflate andrestricts the blood flow in the finger on which it is attached (206),the correlation will drop dramatically since the AC component of thesignal in the compressed finger will be nearly 0. In an embodiment, thesystem 100, 400 is set to determine the systolic blood pressure when thecorrelation drops to a level below a certain correlation threshold,e.g., relatively precipitously. See for example see FIG. 3G which showscorrelation (100% on the y-axis=a correlation ratio of 1) versuspressure cuff inflated pressure (where a relatively precipitous dropoccurs at approximately 125 mm Hg and thus the systolic blood pressureis determined to be about 125 mmHg). For example, the correlationthreshold could be set to 0.85, optionally over a window of time, suchas the 1 second described above. It should be understood that thesesettings (correlation ratio and/or window of time) could be set atalmost any number and those offered above are by way of example only andare optionally variable based depending further clinical testing and/orcomparison to “Gold standard” blood pressure measurements.

Eventually, the pressure cuff 104 is deflated (212), restoring fullblood flow in the finger and at a rate sufficiently slow to detectminute changes in correlation between data readings received from thetwo plethysmographs 102 a/102 b. Based on such changes during deflationof the pressure cuff, blood pressure values such as systolic bloodpressure may be determined.

In some embodiments, systolic BP is determined during deflation (212) bymonitoring a specific change in increase of correlation between datareceived from the two plethysmographs 102 a/102 b and/or using theoscillometric method.

In some embodiments, the diastolic blood pressure may be determinedduring deflation (212) using the oscillometric method, such as describedelsewhere herein.

In practice, the method or protocol varies, optionally dynamically,depending on the patient and/or the treatment scenario. For example, theprocess of inflation and/or deflation of the pressure cuff 104, and theresultant change in correlation, are not typically instantaneous and/ormay vary slightly from patient to patient. As another example, thelength of the window of time may be shorter for a patient with a fasterpulse rate (more pulses per minute means more amplitude peaks and signalchanges in a given time frame, yielding a higher signal to noise ratiowhen comparing signals from the two fingers). As a result, the systolicblood pressure could be a pressure near the beginning, near the middleor near the end of the window of time. In an embodiment, the bloodpressure chosen as the systolic blood pressure and/or the length of thewindow of time are decided as a result of fine-tuning the system 100with high fidelity sensors compared against the conventional goldstandard.

Accordingly, the devices and system disclosed herein may meet medicalgrade requirements.

In some embodiments, the diastolic pressure is determined using a methodsimilar or related to how the systolic blood pressure is determined.Namely, after a quick inflation and then gradual deflation of thepressure cuff scenario, the amplitude of the AC part of theplethysmograph reading in the cuffed finger slowly rises from return ofpulsation (systolic BP) to a constant level, it is believed that thecuff pressure from which constant pulsations are seen from theplethysmograph readings is the diastolic blood pressure. In anembodiment, the diastolic blood pressure reading is confirmed using atleast one additional sensor 102 b which provides information on both theAC and DC components of the plethysmograph reading(s).

In some embodiments, diastolic blood pressure is determined using asecond protocol during deflation (212) from a higher pressure to a lowerpressure where a jump/transition (see an exemplary jump 510 in FIG. 5B)in the plethysmograph reading exceeds a predefined amount (or delta),where a higher pressure immediately at the jump/transition is determinedto be the diastolic blood pressure. It should be noted that inflating(208) and deflating (212) the plethysmograph entirely beneath thediastolic blood pressure will not register a jump/transition sufficientenough to determine a diastolic blood pressure, while inflating (208) toa level above the diastolic blood pressure will cause a “stutter” orjump in the plethysmograph during subsequent deflation (212), whichallows for the determination of diastolic blood pressure (which happensat the stutter).

In some embodiments of the invention, a repetitive, but incrementallyincreasing in inflation pressure, is used in the second protocol tomeasure diastolic blood pressure. For example, at least the actions ofinflating/activating (208) the pressure cuff and then deflating (212)the pressure cuff are repeated at least two or three times, where theinflation pressure of the pressure cuff increases at least slightly eachsuccessive cycle. After at least two or three repeated cycles ofinflating (208) and deflating (212) the recorded pressure duringdeflation (212) where there is a sudden detected change in the behaviorof the plethysmograph is designated to be the diastolic blood pressure.

FIGS. 5A-5C are signal outputs of detected plethysmograph readings froma first finger (with a pressure cuff) and a second finger over timeusing the second protocol, where each of FIG. 5A-5C represents adiscrete progression through the second protocol, in accordance with anembodiment of the invention. The solid black line 502 in each Figurecorresponds to the plethysmograph signal recorded from the firstplethysmograph 402 a, while the dotted line 504 above the solid blackline 502 in each Figure corresponds to the plethysmograph signalrecorded simultaneously from the second plethysmograph 402 bi on thecontrol finger (without the pressure cuff).

In an embodiment of the invention, each one of FIG. 5A, FIG. 5B and FIG.5C is equivalent to 90 sec of recording where the y-axis in each Figurerepresents the amplitude of the plethysmograph 402 a, 402 bi signals (atan arbitrary scale, yet identical in all Figures), the dashed-rectanglesindicate intervals 506 of inflation in the pressure cuff 404 (each at aconstant pressure indicated at mmHg units), and at the end of eachinterval, the pressure at cuff 404 is released to 0 mmHg. In anembodiment of the invention, two main changes in the plethysmographsignal are identified as a function of cuff pressure: 1) the baseline ofthe signal (the DC component) is affected (increased at ˜60-110 mmHg,and decreased at 130 mmHg and above); and, 2) the amplitude of thepulsation (the AC component) decreases as the pressure increases. InFIG. 5A, for example, diastolic blood pressure could be said to be at 60mmHg. In FIG. 5C, it could be 120 mmHg.

In an embodiment of the invention, additional inflating (208) in thesecond protocol after the initial inflation (208) is only performedafter the initial deflating (212) is complete, allowing fluid that mighthave traversed from the intravascular space to the extravascular tissueto “drain” back into the intravascular space before the next inflation(208), for example to avoid accumulation of fluid in extravasculartissue. This pause is represented in FIGS. 5A-5C by the gap 508 betweenintervals 506. Fluid may accumulate in extravascular tissue, forexample, if a protocol was employed in which the cuff is continuouslyinflated until the pressure in the cuff overcomes a systolic pressure.Conducting plethysmograph measurements while fluid is accumulated inextravascular tissue could adversely affect the plethysmograph outputaccuracy, which ideally should provide only output values that relate tointravascular fluid volume. In an embodiment, the system 100, 400 uses(214) sensor information from a plurality of sensors and/or sensormodalities in order to enhance the accuracy of the systolic bloodpressure determination (208) and/or to enhance the accuracy of thedetection of another vital sign. For an intra-modality example, datareceived from one type of sensor (e.g. plethysmograph 102 a/102 b) isoptionally corrected and/or normalized based on data received from adifferent type of sensor (e.g. an accelerometer, where movement sensedby the accelerometer near a specific plethysmograph is used to “correct”data sensed by the plethysmograph where the data is more noisy (e.g.,slightly skewed as a result of the movement)) for example by improvingsignal to noise ratio of the plethysmograph reading, by reducing thenoise component. In a helicopter transport/emergency evacuation typescenario, the at least one additional sensor 102 b is used to filter outsensor noise created by the helicopter rotor blades and/or mechanicalvibrations from the first sensor 102 a. As another example, as analternative to correction as described above, plethysmograph data fromthe vicinity of an accelerometer that shows a lot of movement isoptionally discarded and/or ignored as a result of a certain level ofmovement detection by the accelerometer and data is instead used from adifferent sensor.

For an inter-modality and synergistic example, calculating the pulseusing an oscillometric method allows for anticipation of the peakamplitude in the plethysmograph signal and comparison of the pulsederived from it. This for example enables better signal to noise ratiofor calculating oxygen saturation from the 2 plethysmograph 102 a/102 bwavelengths.

In some embodiments, the system 100, 400 is programmed to choose whichmodality will provide the best result based on the corrective and/ornormalizing methods described above. In some embodiments, the system100, 400 is programmed to select, based for example on at least onequality criterion, the most suitable sensor for collecting datapertaining to a vital sign of interest. At one instance it may forexample be determined that the oscillometric modality is comparably moresuitable to measure a component of blood pressure and/or heart rate thana plethysmograph modality or vice versa. In the former, theplethysmograph modality may yet still used to determine breathing rateand/or blood saturation level.

It is noted that the expression “selection of a sensor”, “choosing asensor”, “using data”, and “selecting data” as well as grammaticalvariations thereof may be used interchangeably.

In an embodiment, once the systolic blood pressure has been determined(208), and/or subsequently diastolic blood pressure and/or any othervital signs have been measured, the patient's condition diagnosis can berendered leading to possible treatment, which may include preventivetreatment to avoid eventually diagnosed forecasted deterioration in thepatient's health condition. In some embodiments, historical datadescriptive of the patient's blood pressure may be analyzed and comparedto give trends in the measured vital signs.

In an embodiment, the system 100, 400 is designed to give weights todifferent vital sign parameters. The system 100, 400 is furtheroperative to determine, based on the weighting of the differentmonitored parameters and integration of the data, if a patient'scondition is expected to worsen in the mid- and long term (hours ordays, as opposed to identification of immediate deterioration), and/oraccording to the number of failing systems and/or data indicative ofseverity.

EXAMPLES

Reference is now made to the following examples, which together with theabove descriptions illustrate some embodiments in a non-limitingfashion.

Example 1

In order to verify the accuracy of two modalities for determining heartrate, an oscillometric method as well as a plethysmograph method areused to provide data about a patient's heart rate. The level ofsynchronization between the oscillometric determined heart rate iscompared with the timing of the peak values provided by theplethysmograph to indicate whether the heart rate readings received fromthe two sensors/modalities are similar, in which case the results areverified.

Example 2

Data obtained from the plethysmograph is optionally used to calculate apatient's breathing rate in the system 100, 400. The weights may be setto a constant value or, alternatively, adjusted, e.g., dynamically whilethe patient is being monitored. In embodiments, the value of one or moreof the weights may set to be constant and the value of one or more otherweights may be dynamically adjusted. The values of weights may be set oradjusted, e.g., based on data descriptive of vital signs received fromthe sensors, e.g., during the monitoring of the patient.

If the system 100, 400 determines that the plethysmograph values aloneare not accurate enough for example, if one or more quality criteria(e.g. signal to noise ratio of plethysmograph readings) are not met, thesystem 100, 400 provides output to the patient through the userinterface which may include an audio prompt, requesting the patient toput one hand on the chest or abdomen such that movement of the chest orabdomen can be measured using accelerometers worn by the patient on thathand. In some embodiments, both of the patient's hands are used todetermine not only breathing rate but also identify breathing pattern byplacing one hand on the chest and/or one hand on the abdomen (e.g.respiration patterns of adults children and/or neonates).

Example 3

In a scenario where the systolic blood pressure is 60 (i.e. very low)but the patient nevertheless exhibits a normal pulse and breathing rate,without showing trend of compensating for the (abnormally) low systolicblood pressure, the system can recheck the patient's systolic bloodpressure value and alarm an attending medical professional if there-measured value continues to reflect an abnormal number. According tothe inventors, known systems do not integrate such data, lack thecapability of providing corresponding output to medical personnel, anddo not employ wearable devices for collecting such data.

The terms “comprises”, “comprising”, “includes”, “including”, “having”and their conjugates mean “including but not limited to”.

As used herein, the singular form “a”, “an” and “the” include pluralreferences unless the context clearly dictates otherwise. For example,the term “a compound” or “at least one compound” may include a pluralityof compounds, including mixtures thereof.

Throughout this application, various embodiments of this invention maybe presented in a range format. It should be understood that thedescription in range format is merely for convenience and brevity andshould not be construed as an inflexible limitation on the scope of theinvention. Accordingly, the description of a range should be consideredto have specifically disclosed all the possible subranges as well asindividual numerical values within that range. For example, descriptionof a range such as from 1 to 6 should be considered to have specificallydisclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numberswithin that range, for example, 1, 2, 3, 4, 5, and 6. This appliesregardless of the breadth of the range.

Whenever a numerical range is indicated herein, it is meant to includeany cited numeral (fractional or integral) within the indicated range.The phrases “ranging/ranges between” a first indicate number and asecond indicate number and “ranging/ranges from” a first indicate number“to” a second indicate number are used herein interchangeably and aremeant to include the first and second indicated numbers and all thefractional and integral numerals therebetween.

As used herein the term “method” refers to manners, means, techniquesand procedures for accomplishing a given task including, but not limitedto, those manners, means, techniques and procedures either known to, orreadily developed from known manners, means, techniques and proceduresby practitioners of the chemical, pharmacological, biological,biochemical and medical arts.

As used herein, the term “treating” includes abrogating, substantiallyinhibiting, slowing or reversing the progression of a condition,substantially ameliorating clinical or aesthetical symptoms of acondition or substantially preventing the appearance of clinical oraesthetical symptoms of a condition.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination or as suitable in any other describedembodiment of the invention. Certain features described in the contextof various embodiments are not to be considered essential features ofthose embodiments, unless the embodiment is inoperative without thoseelements.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims.

Citation or identification of any reference in this application shallnot be construed as an admission that such reference is available asprior art to the present invention, however, to the extent that anycitation or reference in this application does not contradict what isstated herein, it is incorporated by reference. To the extent thatsection headings are used, they should not be construed as necessarilylimiting.

What is claimed is:
 1. A system for measuring diastolic and/or systolicblood pressure of a patient, the system comprising: first and secondplethysmographs removably attachable to a same hand of a patient; apressure cuff removably attachable to a finger of the same hand, andconfigured to occlude blood flow in the finger in an inflated state ofthe pressure cuff; a pump configured to inflate and deflate the pressurecuff in intervals for a plurality of times; and a processor configuredto: (a) determine the diastolic blood pressure to be a pressure to whichthe pressure cuff was inflated when a transition in the reading from theplethysmographs exceeds a predefined amount; and (b) determine a levelof correspondence between a first signal from the first plethysmographand a second signal from the second plethysmograph; and (c) determinethe systolic blood pressure of the patient based on a change in thelevel of correspondence.
 2. The system according to claim 1, wherein thepump is configured to inflate the pressure cuff such that: 1) theinflating in each of the plurality of times is at least to a slightlyhigher pressure than the inflating before it; 2) additional inflating isonly performed after the initial deflating is complete.
 3. The systemaccording to claim 1, wherein the processor is configured to determinethe systolic blood pressure of the patient based on the change in thelevel of correspondence when a correlation drops precipitously to alevel below a certain correlation threshold.
 4. The system according toclaim 1, wherein the first and second plethysmographs are removablyattachable to first and second fingers of the same hand, and wherein thecuff is removably attachable to the first finger between the firstplethysmograph and a respective ipsilateral palm of the patient.
 5. Thesystem according to claim 1, wherein the first and second plethysmographcomprise photo-plethysmographs configured to detect at least twowavelengths.
 6. The system according to claim 1, wherein the pumpfurther comprises a valve configured to control flow rate duringdeflation of the pump.
 7. The system according to claim 1, wherein thepump comprises a syringe.
 8. The system according to claim 1, whereinthe processor is located remotely from the patient.
 9. The systemaccording to claim 1, wherein signals in the system are communicatedwirelessly.
 10. The system according to claim 1, wherein the system isconfigured to be wearable by the patient.
 11. The system according toclaim 1, wherein at least a portion of the system is configured to bewearable by an attending medical professional.
 12. The system accordingto claim 1, wherein the processor is further configured to determine,from received signals, at least one of: mean arterial pressure, pulserate, breathing rate, breathing pattern, hemoglobin oxygen saturationlevel, motor function, temperature, and cognitive ability of thepatient.
 13. A method comprising: removably attaching a firstplethysmograph to a hand of a patient; removably attaching a secondplethysmograph to the same hand of the patient; removably attaching apressure cuff to a finger of the same hand between the firstplethysmograph and a respective ipsilateral palm of the patient;occluding blood flow in the finger by inflating and deflating thepressure cuff in intervals for a plurality of times; determining a levelof correspondence between a first signal from the first plethysmographand a second signal from the second plethysmograph; and determiningsystolic blood pressure of the patient based on a change in the level ofcorrespondence.
 14. The method according to claim 13, further comprisingdetermining diastolic blood pressure to be a pressure to which thepressure cuff was inflated when a transition in the reading from theplethysmographs exceeds a predefined amount.
 15. The method according toclaim 13, wherein inflating the pressure cuff comprises 1) the inflatingin each of the plurality of times is at least to a slightly higherpressure than the inflating before it; 2) additional inflating is onlyperformed after the initial deflating is complete.
 16. The methodaccording to claim 13, wherein determining the systolic blood pressureof the patient based on the change in the level of correspondencecomprises determining when a correlation drops precipitously to a levelbelow a certain correlation threshold.
 17. The method according to claim13, wherein removably attaching the first and second plethysmographscomprises removably attaching the first and second plethysmographs tofirst and second fingers of the same hand of the patient.
 18. A methodcomprising: removably attaching first and second plethysmographs tofirst and second fingers of a patient; in intervals, occluding bloodflow in the first finger of the patient; determining (i) a parameter ofblood pressure of the patient by determining a change in a level ofcorrespondence between a first signal from the first plethysmograph anda second signal from the second plethysmograph; and (ii) a parameter ofblood pressure of the patient based on oscillometry measurements fromthe first finger; and calculating systolic and diastolic blood pressureof the patient based on the determining.
 19. The method according toclaim 18, wherein removably attaching the first and secondplethysmographs, comprises removably attaching plethysmographs to firstand second fingers of the same hand of the patient.